Lifting jack



'A. D. POWELL. 11mm; JACK.

APPLICATION FILED OCT. 26, 1920.

1,422,781. Patented July 11, 1922..

4 SHEETS-SHEET 1.

1770917 Z'or' A. D. POWELL.

LIETING JACK. APPLIATION man ocnz. 1920.

A. D. POWELL.

LIFTING JACK.

APPLICATION FILED OCT. 26, 1920. 1,422,781.. Patented y 11,1922.

4 SHEETSSHEET 3.

- Fiyi Ifluenfor 17D. Powell LIFTING JACK.

weaver.

Specification of Letters Patent.

Patented July ii, race.

Application filed October 26, 1920. Serial No. 419,597.

To aZZ whom it may concern:.

Be it known that I, AnonrsALn DOUGLAS POWELL, subject of His Majesty theKing of England, and resident of Braintree, in the county of Essex andKingdom of England, have invented certain new and useful Improvements inor Relating to Lifting. Jacks (for which I have filed an application inEngland Dec. 10, 1919, No. 30,987), of which the following is aspecification.

This invention relates to improvements in lifting jacks of the type inwhich the lifting operation is accomplished mechanically and thelowering is controlled by fluid pressure.

The object of this invention is to provide an improved method ofoperating a lifting jack of the above type.

With this object in view the invention is characterized in that meansare provided whereby the lowering operation cannot be effected beforethe manually operated pawl is disengaged.

The invention also consists in providing means, adapted to be actuatedby the mechanical means, for effecting the lowering of the jack, andmeans to prevent the jack being lowered inadvertently.

The invention will now be described with reference to the accompanyingdrawings, in which Figure 1 is a sectional elevation of one form oflifting jack constructed according to this invention; I

Figure 2 is a plan thereof;

Fig. 3 is a side view;

F ig. &' is a similar view to Figure 1, showing the jack in its loweringposition;

Figure 5 is a sectional elevation of a moditied form of lifting jack;

Figure 6 is a plan thereof;

Figure 7 is a side view;

Figure 8 is a similar view to Figure 5 showing the jack in its loweringposition;

Figure 9 is a sectional elevation of a further modified construction,and

Figure 10 is a similar view showing the jack in its lowering position.

As shown more particularly in Figures 1 to l, the base or pedestal 1 ofthe lifting jack comprises acontainer 2 for fluid such as oil and ahousing or sustaining cylinder 3 in which is slidably mounted apiston 4forming part of a rack or toothed spindle 5 which supports a crutch 6which is mounted on an other spindle 7 preferably slidably andadjustably mounted in the before mentioned piston spindle 5 in the usualmanner. The pedestal 1 is slotted at 8 for the reception of a pawl 9which is adapted to engage with the rack teeth 10 formed on the spindle5. The pawl 9 is mounted in a lever or handle carrier 11 which ispivoted at 12 to the pedestal 1. A suitable slot 18 is formed in thecarrier 11 for the reception of an operating handle or lever 14. Theinner end of this lever 1 1 is adapted to engage, when in normal oroperativc position for lifting, against a spring 15 to hold the pawl 9in engagement with the rack teeth 10. The pawl 9 which is suitablyweighted at 16 is normally held in engagement with the rack teeth 10 byits abutment against the upper flange 17 of the pedestal 1 but upon thepartial withdrawal of the lever 14: and the further lowering thereof thepawl 9 will be disengaged to effect the lowering of the jack. Thepivoted carrier 11 is formed with a cam or the like 18 which is adaptedto engage with a planger 19 which is kept in its normal position by aspring 20. The lower end of the plunger 19 is adapted to engage with aball or other form of valve 21 which is kept in'its normal or closedposition by a spring 22. This valve 21 is adapted to automaticallycontrol the flow of fluid from the container 2 into the housing 3 whenthe jack is raised.

In operation and when it is desired to raise the jack the lever 1a isinserted in the slot 13 and moved up and down in the usual manner tooperate the pawl 9 and effect the raising of the spindle 5. The fluidfrom the container2will be drawn into the housing 3 through theautomatic valve 21 and thereby prevent the lowering of the jack. Whenthe lever 14L is lowered to the position shown in Figure 1 the pawlstrikes the flange 17 and prevents the cam 18 from engaging the plunger19 and the inadvertent opening of the valve 21. When it is desired tolower the jack the lever 1 1- is partially withdrawn from its socket andaway from the spring 15 of the pawl 9. Upon further downward movement ofthe lever 1 1, after the pawl '9 is allowed to fall out of engagementwith the rack by its weighted projection 16, the cam shaped projection18 will engage the plunger 19 to open the valve 21 and allow the fluidto flow back to the container 2 and steadily lower the jack.

In a modified construction as shown in Figures 5 to 8 the rack teeth 10on the spindle 5 are engaged by a pinion wheel which is mounted on ashaft 24c and secured to a ratchet wheel 25. About this ratchet wheel 25is mounted for oscillation an op erating lever carrier 26 which isformed with a slot 13 for the reception of thclcver 1 1 which in thiscase is angularly shaped at its end to-engagewith the ratchetteeth-ofthe wheel 25. The lever .14- .is formed or provided with a pin orprojection 27 which is adapted to engage with a lug 28on the pinionhousing of the pedestal 1 and thus preventthe cam shaped projection 18from engaging with the plunger 19 and the inadvertent opening of thevalve 21. Suitable co-operating stops 29 are provided-on the carrier 26and .pedestal 1 to limit-the upward movement of the lever 14:.

The lifting operation is performedin the ordinary manner by the up anddown movement of the lever 14 and the jack will be. retained in itsraised position by the fluid which passes, through the medium of thevalve 21, from the container 2 into the'housing 3. WVhen it is desiredtolower the jack the, lever 14 is partially withdrawn and 'the pin27.thereonis moved along a suitable slot cut in the sideof the carrier26 so as to be outofengagement with the stop 28. The lever 14 can now belowered to open the valve ,21 throughthemedium ofthe cam 18 and plunger.19. .The'fluid supporting the jack inits raisedposition willinow flowback into the container 2 and the jack will be lowered.

In a further .modified construction, as shownin Figures 9'and'10 aspring pressed pawl 30 which is adapted to actuate the ratchet wheel25'is mounted in a carrier 31 which is pivoted on the operating levercarrier-26. The rear end of the carrier 31 is formed with a lug orextension 32, which passes through a slot in the carrier 26 and isadapted to be engaged bythe lever letto hold the pawl inpositionforco-operating withthe ratchet wheel 25. Upon the removal of the leverlet the pawl 30 will be moved out of its co-operative position withtheratchet wheel 25 by the spring 33. In this construction the automaticnon-return valve 21 is opened as before by the pressure ofthefluidentering the sustaining cylinder 3 when the jack is raised. =VVhen it isdesired to-lower the jack the lever 14-=is inserted in an additionalcarrier 3 1 which is pivoted preferably atthe other side of the housing.Upon downwardmovement of theposition.

In order to allow fluid to rapidly follow the raising of the jack, it isnecessary that the port shouldbe of the-maximum size,

but it will be obvious that if the release valve was fully opened by itsplunger the jack would be lowered more rapidly than desired. To obviatethis provision is made whereby the plunger actuating the release valverestricts the area of'the port before the valve is opened, for instanceas shown more particularly in Figure 4.

- f-desired, a non-return valve, as shown in Figures-9 and 10, may befitted to any of the jacks above described but in any of thecasesthelowering will-be effected by the manually operated valve.

It will be seen that in the jacks above described there will be noleakage of the oil or other fluid employed to sustain the jacks in theirraised positionas there is no need to maintain atmospheric pressureduring their. operation.

What I claim is '1. A lifting jack, comprising a base formed'forcontaining fluid and with a spindle housing, a spindle slidablein thehousing formed with ratchet teeth and'provided with a crutch at theupper end, the base be ing formed with a passage from the fluidcontainer .to the spindle housing, a valve mounted in the passage andclosing it to a reverse flow, and means for elevating the spindle, saidmeans also being adapted to operate the valvetope-rmit a reverse flow offluid.

2. A lifting jack, comprising a base formed with a fluid container, aspindle housing .and a passage establishing communication therebetween,means operating automatically to prevent a flow through the passage fromthe housing to the container, a spindle slidable in the housing, andmeans for sliding the spindle in the housing, said means being adaptedto actuate the firstmentionedmeans to permit a flow of fluid to thecontainer.

3. A lifting jack, comprising a base formed with a fluid container, .aspindle housing and a passage establishing commu nication therebetween',means mounted in the body and controlling thepassage permitting aone-way flow of fluid, a spindle slidable in the spindle housing. andoperating means adapted to elevate the spindle in one position thereofand ina second position being adapted to actuate said means inthe bodyto permit aback flow'of fluid.

4. A lifting jack, comprising a base formed with a fluid container, aspindle housingand a passageestablishing communication therebetween,means permitting a one-way flowzof fluid in the.passage,.aspindleslidably mounted in thehousing, operating means adapted touelevatethespindle, saidoperatingmeans being adapted to actuate the means in thepassage to permit a reverse flow of fluid, and means for preventing theoperation of the first-mentioned means during the operation of theoperating means in elevating the spindle.

5. A lifting jack, comprising a base formed with a fluid container, aspindle housing and a passage establishing communication therebetween, acheck valve mounted in the passage for normally preventing a flow fromthe spindle housing to the container, a plunger slidable in the baseadapted to operate the check valve to permit a back flow, a spindleslidable in the housing, operating means for elevating the spindlewithin the limits of one position thereof and in another positionthereof adapted to engage the plunger for operating the check valve.

6. A lifting jack, comprising a base formed with a fluid container, aspindle housing and a passage establishing communication therebetween, acheck valve mounted in the passage for preventing a reverse flow offluid, a plunger slidably mounted in the base adapted to engage thecheck valve, said plunger being formed to control the reverse flow ofthe fluid, a spindle mounted in the housing, and operating means adaptedto elevate the spindle and also adapted to move the plunger and operatethe check valve to permit a reverse flow of the fluid.

7. A lifting ack, comprising a base formed with a fluid container, aspindle housing and a passage establishing communication therebetween, acheck valve for preventing a reverse flow in the passage, a spindleslidable in the housing, a handle carrier pivotally mounted in thehousing and having a pawl pivoted thereto adapted to engage teeth formedon the spindle, a handle for operating the handle carrier and the pawlto elevate the spindle, and means operated by the handle carrier forengaging the check valve to permit a reverse flow in the passage.

8. A liftingjack, comprising a base formed with a fluid container, aspindle housing and a passage establishing communication therebetween, acheck valve mounted in the passage preventing a reverse flow of thefluid, a spindle formed with ratchet teeth slidably mounted in thehousing, a handle carrier pivoted in the base having a pawl pivotallymounted thereto for engaging the rack on the spindle for elevating thespindle in the operation thereof, and means operated by the handlecarrier for operating the check valve to permit a reverse flow, saidpawl being formed to prevent the operation of the check valve during theengagement of the pawl with the rack.

9. A lifting jack, comprising a base formed with a fluid container, aspindle housing and a passage establishing communication therebetween, acheck valve mounted in the passage preventing a reverse flow therein, aplunger slidably mounted in the base adapted to engage the check valve,a spindle formed with ratchet teeth slidable in the housing, a handlecarrier pivoted in the base and having a pawl pivoted thereto adapted toengage the rack for elevating the spindle, a

handle adapted for insertion in the handle carrier and adapted tooperate the pawl to engage the rack for elevating the spindle in theoperation of the handle carrier, said handle carrier being formed with acam for operating the plunger and check valve to permit a reverse flowin the passage, the operation of the plunger by the handle carrier beingprevented while the handle projects the pawl into engagement with therack.

10. A lifting jack, comprising a base formed with a fluid container, aspindle housing and a-passage establishing communication therebetween, acheck valve for preventing a reverse flow in the passage, a plungerslidable in the base adapted to engage the check valve, a spindle formedwith ratchet teeth slidably mounted in the housing, a handle carrierpivotally mounted in the base having a pawl pivoted thereto adapted toengage the rack and formed with a handle receiving portion, a cam forengaging the plunger, and a handle slidably mounted in the handlereceiving portion adapted in one position thereof to project the pawlfor operative engagement-with the rack for elevating the spindle, and inanother position thereof to permit the movement of the pawl to aninoperative position and the engagement of the cam with the plunger tooperate the check valve to permit a reverse flow.

In testimony whereof I have hereunto signed my name.

ARCHIBALD DOUGLAS POWELL.

